Short ppt on GCMS

1. Submitted by
•Swapnil S. Barskar Msc. GPB Reg No. 2010119009
•Nanasaheb R. Markad Ph. D. ( Agril. Biotech) Reg No. 1010119016
•Yogeshwar G. Patil Ph. D. Agronomy Reg No. 1010119028
Submitted to
Dr. N. J. Patel.
Associate Professor
Department of Agril. Biochemistry
Assignment on
Course Name : Techniques in Biochemistry ( Biochem 505)
Gas Chromatography and Mass Spectrometry ( GC- MS)

2.  Introduction
 Instrumentation
 Gas Chromatography
 Interface
 Mass Spectrometer
 Data System
 Analysis of Results
 Calibration of Instrument
 Applications
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3. term hyphenated techniques introduced by
Hirschfeld
“It refers to an on-line combination of a
chromatographic sepration technique
with a sensitive and element-specific
Spectroscopic detector” .
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Hybrid
Techniques
Chromatography Spectroscopy

4. 4
Gas
Chromatography
It separates
components of
sample
Interface
Combines both
techniques by
removing pressure
incompatibility
problem between
GC and MS
Mass spectrometry
Ionise eluted
component and
separately identify
it according to its
mass to charge
ratio
Gas chromatography-mass spectrometry (GC-MS) is
a hyphenated technique ; consisting of two
analytical procedures in sequence, namely a Gas
Chromatography (GC) separation followed by Mass
Spectroscopy (MS) detection.

5.  Gas chromatography-mass spectroscopy (GC-
MS) is a hyphenated analytical technique
 sensitive but also specific and reliable
 GC can separate volatile and semi-volatile
compounds with great resolution, but it cannot
identify them.
 MS provide detailed structural information on
most compounds such that they can be exactly
identified, but can’t readily separate them.
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6.  Therefore, combination of both instruments
have been proposed shortly after the
development of GC in the mid-1950s.
 We obtain both qualitative and quantitative
information of our sample in a single run within
the same instrument
 Today computerized GC/MS instruments are
widely used in environmental monitoring , in the
regulation of agriculture and food safety , and
in the discovery and production of medicine.
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7.  The sample solution is injected into the GC inlet
where it is vaporized and carried in a
chromatographic column by the carrier gas (usually
helium).
 The sample flows through the column and the
compounds comprising the mixture of interest are
separated due to their relative interaction with the
coating of the column (stationary phase) and the
carrier gas (mobile phase).
 The latter part of the column passes through a
heated transfer line and ends at the entrance to ion
source where compounds eluting from the column
are converted to ions and detected according to
their mass to charge m/z ratio 7

8. GC-MS comprise following major blocks
1. the gas chromatograph
2. Interface
3. the mass spectrometer
4. A data system is necessary to handle results
obtained during a sample run
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9. 9
Fig 1:The insides of the GC-MS, with the column of the gas
chromatograph in the oven on the right.

10.  Gas chromatography leads to Separation of
volatile organic compounds
 Separation occurs as a result of unique
equilibrium established between the solutes
and the stationary phase (the GC column)
 An inert carrier gas carries the solutes
through the column
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11. 11
Basic Components:
 Carrier Gas
 Gas Controls
 The Injector
 The Column
 The Oven
 The Detector
(Mass Spectrometer)

12.  Packed column injectors
 Split Injection
 Split less Injection
 Programmed Split/Split less Injector
 Programmed On-Column Injector
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13. Split Injector Split less Injector
Split injector

14.  There are two kinds of columns used i.e.
Packed or capillary columns
 The gas chromatograph GCMS utilizes a
capillary column which most widely used
columns for GC-MS are those in which the
stationary phase has been chemically bonded
to the fused silica
 DB-5 is a common trade name.
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15. Fig1.3 :( a) Uninstalled Capillary Columns (b)Installed capillary
Columns
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16.  The pressure incompatibility problem
between GC and MS was solved by Inserting an
Interface.
 Interface join GC with MS. There are many
interfaces like Jet, Electrospray, Thermospray,
Direct electrical ionization, Moving wire or Belt
interface.
 Commercially available interface are:
1. Jet Interface
2. Direct Interface
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17.  It works on the differences in diffusibility between
the carrier gas and the organic compound.
 These jet separators work well at the higher
carrier gas flow rates (10 to 40 mL/min) is sprayed
through a small nozzle, indicated into a partially
evacuated chamber (about 10–2 torr).
 The carrier gas is a small molecule with a high
diffusion coefficient, whereas the organic
molecules have much lower diffusion coefficients.
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18. Fig:1.4: Jet Interface
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19.  Most GC-MS interfacing is now done by simply
inserting the capillary column directly into
the ion source.
 Using a column that is 25 to 30 m long by
220 to 250 μm inner diameter gives an ion
source pressure of 10–6 to 10–5 torr
 This gives a helium or hydrogen GC carrier
gas velocity of 25 to 35 cm/sec.
 Pumping Speed of Mass spectrometer should
be high
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20. Fig1.5 :Direct Capillary Column Interface
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Capillary Column Interface

21. “Mass spectrometry is a technique used
for measuring the molecular weight and
determining the molecular formula of an
organic compound”
In general a mass spectrometer consists of
 an ion source,
 High-vacuum system
 a mass-selective analyzer,
 an ion collector
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22. Electron Impact Ioniser
• In an electron-impact mass spectrometer (EI-
MS), a molecule is vaporized and ionized by
bombardment with a beam of high-energy
electrons.
• The energy of the electrons is ~ 1600 kcal (or
70eV).
• The electron beam ionizes the molecule by
causing it to eject an electron.
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23. 23

24. CI begins with ionization of methane, ammonia or
another gas,
creating a radical cation (e.g. CH4
•+ or NH3
•+).
sample molecule M will produce MH•+ molecular
ions.
positively charged species will be detected.
CI Used for determination of molecular ion while EI
for detailed structure Information.
Hence the two methods are complementary.
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25. 25

26. • Mass analyzers scan or select ions over a particular
m/z range.
• According to the accuracy, range and sensitivity of
an instrument, common types of mass analyzers are:
•Quadrupole,
•Magnetic sector,
•Time-of-flight,
•Fourier transform-ion cyclotron resonance (FT-ICR).
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Mass Analyzers

27. 27
 Quadrupoles are four precisely parallel rods with a
direct current (DC) voltage. The field on the
quadrupoles determines which ions are allowed to
reach the detector. Quadrupoles thus function as a
mass filter.

28.  GCMS system along with a powerful (but small)
computer acting as a data system.
 Data System of GC-MS used to identify and
measure the concentration of one or more
components in a complex mixture.
 Quantification can be based on peak areas
mass chromatograms
 selected ion monitoring(SIM).
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29.  With the selected ion monitoring technique, the
mass spectrometer is not scanned over all masses;
instead, the instrument jumps from one selected
mass to another.
 the mass spectrometer spends much more time at
a given mass
Difference b/w
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SELECTED ION MONITORING
the responses from only a
few preselected masses are
recorded
MASS CHROMATOGRAM
all of the masses are
scanned; thus, no pre-
selection is required

30. Fig1.8 : Schematic of a Gas Chromatography-Mass
Spectrometry (GC-MS) Instrument
interface
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31.  State
 compounds must be in solution form
 The solvent must be volatile and organic
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32.  In addition to sample preparation time, the
instrumental analysis time usually is fixed by
the duration of the gas chromatographic run,
typically between 20 and 100 min.
 Data analysis can take another 1 to 20 hr (or
more) depending on the level of detail
necessary.
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33.  Petrochemical and hydrocarbons analysis
 Geochemical research
 Forensic (arson, explosives, drugs, unknowns)
 Environmental analysis
 Pesticide analysis, food safety and quality
 Pharmaceutical and drug analysis
 Clinical toxicology
 Food and fragrance
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